“Rudo y Cursi” is a lively and engaging comedy that highlights some drama in its storyline. Regrettably, in the end, feels a little thin, largely because it is unsure of how earnestly to treat its own lessons about fate, ambition and brotherly love. There is a lot of velocity in this ultimately familiar tale of rising and falling, but not much gravity. “Rudo y Cursi” is partly about the consequences of taking a game much too seriously, but at the same time it treats everything else — life, death, love, money — like a game.

Beto (Diego Luna) and Tato Verdusco (Gael Garcia Bernal) are half brothers who work together at a banana plantation and live with their extended family in a village in southern Mexico. When the two of them are suddenly (and somewhat improbably) plucked from rural proletarian obscurity and turned into professional soccer players in Mexico City, they achieve fame as Rudo and Cursi, nicknames that can be translated more or less as tough and corny.

But Mr. Cuarón also has trouble managing the tone of the film as it swerves from light-hearted absurdity toward a darker, more cynical view of its characters and their fate. Too often he allows “Rudo y Cursi” to coast on the likeability of its stars, who seem at times to be enjoying themselves more than their characters are able to.